Here in Australia the population debate has been raging for decades. The crux – despite our size, much of Australia is arid or semi-arid. We are the driest inhabited continent on Earth, with most of the arable land concentrated in a strip near the coast. Most of the population is there too (90% or more). We also have fragile and increasingly-degraded ecosystems, with water access and equity a major issue.
Should Australia rapidly increase population by 60%?
The debate currently hinges on whether Australia should significantly increase her population (from the current 21.4 million) to 36 million souls. On one side sits the economic rationalists who look at all those extra consumers with greedy eyes while chanting “growth and GDP”. On the other, environmental and other groups who can see that we are irreversibly reducing our carrying capacity with our current population, let alone a much larger one.
I found an interesting take on it today: a short pdf from The Australia Institute. In part it reads:
Australia is a nation of migrants; the first intake sought no permission to settle here. Migration is, and is likely to remain, an important part of what makes the Australian population the diverse and dynamic society that it has become. But the benefits of migration should not be conflated with the benefits of an ever-increasing population. As the data presented above show, there is no reason for Australians to be forced to choose between being open, inclusive and rapidly growing or being closed, exclusive and stable.
The onus of proof should be on those who wish to see our population burgeon to make the case for it. Similarly, if we are to increase our population by 60 per cent in the next four decades we should invest in the infrastructure we will need before we invite new citizens, not after they arrive.
In this era of evidence-based policy, it seems strange that for all the government inquiries that have been held there is yet to be a major scientific, social and economic analysis of the impact of rapid population growth in Australia. While it might be hard to agree on exactly how many people Australia can handle, it may be much easier to agree that much of our infrastructure, natural, physical and social, is already showing signs of stress.
Image credit: Christopher Chan.
| Hack the Planet: Science's Best Hope - or Worst Nightmare - for Averting Climate Catastrophe |
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An inside tour of the incredible—and probably dangerous—plans to counteract the effects of climate change through experiments that range from the plausible to the fantastic
David Battisti had arrived in Cambridge expecting a bloodbath. So had many of the other scientists who had joined him for an invitation-only workshop on climate science in 2007, with geoengineering at the top of the agenda. We can’t take deliberately altering the atmosphere seriously, he thought, because there’s no way we’ll ever know enough to control it. But by the second day, with bad climate news piling on bad climate news, he was having second thoughts. When the scientists voted in a straw poll on whether to support geoengineering research, Battisti, filled with fear about the future, voted in favor.
While the pernicious effects of global warming are clear, efforts to reduce the carbon emissions that cause it have fallen far short of what’s needed. Some scientists have started exploring more direct and radical ways to cool the planet, such as:
· Pouring reflective pollution into the upper atmosphere
· Making clouds brighter
· Growing enormous blooms of algae in the ocean
Schemes that were science fiction just a few years ago have become earnest plans being studied by alarmed scientists, determined to avoid a climate catastrophe. In Hack the Planet, Science magazine reporter Eli Kintisch looks more closely at this array of ideas and characters, asking if these risky schemes will work, and just how geoengineering is changing the world.
Scientists are developing geoengineering techniques for worst-case scenarios. But what would those desperate times look like? Kintisch outlines four circumstances: collapsing ice sheets, megadroughts, a catastrophic methane release, and slowing of the global ocean conveyor belt.
As incredible and outlandish as many of these plans may seem, could they soon become our only hope for avoiding calamity? Or will the plans of brilliant and well-intentioned scientists cause unforeseeable disasters as they play out in the real world? And does the advent of geoengineering mean that humanity has failed in its role as steward of the planet—or taken on a new responsibility? Kintisch lays out the possibilities and dangers of geoengineering in a time of planetary tipping points. His investigation is required reading as the debate over global warming shifts to whether humanity should Hack the Planet.
An interesting article published in the current issue of Environmental Science & Technology explains why we have entered a new geologic period called the Anthropocene.
Denoting the current period of human-dominated activity, adopting this term recognises that human activity is changing the Earth on a scale comparable with some of the major events of the ancient past, and that some of these changes are now seen as permanent (even on geological time-scales).
Stratigraphy of the Grand Canyon
One of the first steps to formalising this term occurred in 2008 when the Geological Society of London decided that there was merit in considering the possible formalization of this term (meaning that it might eventually join other such units on the Geological Time Scale like the Cambrian, Jurassic and Pleistocene). Now the first (of many) formal steps are being taken by international bodies like the International Union of Geological Sciences.
Evidence of massive environmental change
First, how have the actions of humans altered the course of Earth’s deep history? The answers boil down to the unprecedented rise in human numbers since the early nineteenth century—from under a billion then to over six billion now, set to be nine billion or more by mid-century. This population growth is intimately linked with massive expansion in the use of fossil fuels, which powered the Industrial Revolution, and allowed the mechanization of agriculture that enabled those additional billions to be fed.
The change to the earth’s surface created by the building of megacities have increased by an order of magnitude the natural processes of erosion and sedimentation. The authors of the article say that while this is remarkable (from the geological point of view), if city construction declines or stops altogether then natural geomorphological processes will once again take over (as evidenced by abandoned cities such as Angkor in Cambodia).
We are probably at the start of the earth's sixth mass-extinction event.
Probably more far-reaching are the effects on the earth’s chemical and biological components. Most readers of this blog already understand that the atmospheric concentrations of trace compounds (especially carbon dioxide and methane) have changed considerably (and are of course having major effects on our planet).
We know the effects:
- Global temperature increase (especially at the poles)
- Melting polar regions and glaciers
- Sea-level rise
- Ocean acidification
- Species migration where possible
- Species extinction (at 100-1000 times the background rate, and expected to increase by a further factor of 10 this century)
Global temperature rises will have far-reaching consequences for the biosphere. Species will migrate (if they are able to) to track their optimum climate belt, a phenomenon more pronounced in the oceans than on land – changes in, say, larval hatching times can cause cascade-like changes in entire ecosystems, when these larvae act as food for other animals.
The article goes into some detail about how the boundaries between different geological periods are determined – well worth a read if geology interests you!
(The) current human-driven wave of extinctions looks set to become Earth’s sixth great extinction event.
The authors conclude that …”the Anthropocene represents a new phase in the history of both humankind and of the Earth, when natural forces and human forces became intertwined, so that the fate of one determines the fate of the other. Geologically, this is a remarkable episode in the history of this planet.”
The folks at the Permaculture Drylands Institute (now out of print) have scanned and made available for free some of the best permaculture articles published in the Journal.
Articles from the Permaculture Drylands Journal now available online.
Please support them by having a look at what they have to offer. While we’re on the subject of permaculture, take a look at David Holmgren’s permaculture site. As you probably know, David co-originated the permaculture movement with Bill Mollison.
Holmgren's latest permaculture DVD is one of the best.
Climate change is likely to affect mental health in several ways. Climate change is associated with increasingly frequent and severe weather events, which cause extensive infrastructure damage, economic slowdown, and interruptions of medical and psychiatric care. These events, and the lifestyle changes that can result, are associated with increased mental health burdens.
Climate change is already causing a range of mental health impacts.
Extreme weather events cause relocation and displacement and rupture people’s relationships with place. Other effects of climate change, including sea-level rise and other ecological changes, will also cause displacement and undermine longstanding human relationships with supporting local ecosystems.
From the loss of life, dislocation, infrastructure loss, and interruption of medical care, extreme weather events such as severe hurricanes can be associated with increases in depression, grief and post-traumatic stress disorder. Relocation and displacement can also have significant mental health effects, and are independently associated with major depression as well.
On another level, the magnitude of the climate crisis, and worry over future effects on health and the environment, have already generated concern in some parts of the general population. The degree of this health burden relative to other strains on mental health is unknown, but points to the necessity for effective public health communication that inspires action rather than stress and despair.
I just added a new climate change glossary to this site. There are around 40 103 terms ranging from “aerosol” to “weather”.
| The Health Practitioners Guide to Climate Change: Diagnosis and Cure |
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Heat waves, or extreme heat events, are characterized by several days of temperatures greater than 90° F; warm, stagnant air masses; and consecutive nights with higher–than-usual minimum temperatures. As a result of climate change, heat waves are expected to increase in severity and frequency, particularly in the northern latitudes. The nature of the temperature shifts brought by climate change, which include both a shift in the average temperature overall as well as an increase in temperature variability, are depicted in the graphs below. The images show that there is likely to be much more hot weather with climate change, and more record hot weather, as well.
Effects of increased average temperatures and climate-changed induced temperature variability on the number of hot days.
Heat waves are already the most deadly weather-related exposure in the U.S., and account for more deaths annually than hurricanes, tornadoes, floods, and earthquakes combined. Children and older adults are at greater risk from heat. Other risk factors for heat-related death include living alone, lack of air-conditioning, and use of certain medications. Additionally, there is an element of adjustment to heat as body processes change to compensate for increased temperatures; this can be protective during heat waves.
Climate change will bring more heat waves to the U.S. Increases in the number of people living in cities, as well as population aging, will further increase heat-related health risks. Studies suggest that, if current emissions hold steady, excess heat-related deaths in the U.S. could climb from an average of about 700 each year currently, to between 3,000 and 5,000 per year by 2050.
Effective strategies have been identified for preventing heat-related illness and death among individuals and populations. Individually, gaining access to cooler temperatures, usually achieved through air conditioning, is key to preparing for heat waves. Checking elderly and homebound neighbors, relatives, and acquaintances during heat waves can be life-saving. Avoiding or rescheduling strenuous activities during heat waves, drinking lots of water, and dressing in light-colored, loose fitting clothing are all important behavior changes.
Heatwaves due to climate change will be more frequent, hotter and longer.
On a community level, municipal heat response plans can be very effective, and vulnerability mapping, a process that highlights the locations of vulnerable populations, can target efforts even more effectively. Urban planning that increases green space, reduces heat build-up in buildings and other structures, and decreases the size and intensity of the urban heat island is also an effective strategy.
Learn More:
CDC e-learning course on heat-related illnesses.
Source: http://www.cdc.gov/climatechange/effects/heat.htm
There has been lots of talk lately about Antarctica and whether or not the continent’s giant ice sheet is melting. One new paper, asserting that there has been less surface melting recently than in past years, has been cited as “proof” that there’s no global warming. Other evidence that the amount of sea ice around Antarctica seems to be increasing slightly is being used in the same way. But both of these data points are misleading.
Basically the sceptics are cherry-picking the data to support their own case, and they have been looking in the wrong place.
Gravity data collected from space using NASA’s Grace satellite show that Antarctica has been losing more than a hundred cubic kilometers (24 cubic miles) of ice each year since 2002. And the latest data reveals that ice loss is accelerating.
Antarctica is losing ice mass at an accelerating rate
Most of the loss is occurring in West Antarctica. A series of islands covered by ice (think of it as a frozen Hawaii with penguins), much of the West Antarctic Ice Sheet (or WAIS) is actually sitting on the floor of the Southern Ocean. Parts of it are more than 1.7 kilometers (1 mile) below sea level.
Of the West Antarctic islands, Pine Island is the largest. It has the largest ice stream in West Antarctica (the Pine Island Glacier). The WAIS – if it melted completely – would raise sea level by 5 to 7 meters (16 to 23 feet). And the Pine Island Glacier would contribute about 10 percent of that.
Since the early 1990s, European and Canadian satellites have been collecting radar data from West Antarctica. These radar data can reveal ice motion and, by the late 1990s, there was enough data for scientists to measure the annual motion of the Pine Island Glacier.
Using radar information collected between 1992 and 1996, oceanographer Eric Rignot, based at NASA’s Jet Propulsion Laboratory, found that the Pine Island Glacier’s “grounding line” — the line between the glacier’s floating section and the part of the glacier that rests on the sea floor — had retreated rapidly towards the land. That meant that the glacier was losing mass. He attributed the retreat to the warming waters around West Antarctica. But with only a few years of data, he couldn’t say whether the retreat was a temporary, natural anomaly or a longer-term trend from global warming.
Climate change will have major impacts on Antarctic species
Rignot’s paper surprised many people. JPL scientist Ron Kwok saw it as demonstrating that “the old idea that glaciers move really slowly isn’t true any more.” One result was that a lot more people started to use the radar data to examine much more of Antarctica. A major review published in 2009 found that Rignot’s Pine Island Glacier finding hadn’t been a fluke: a large majority of the marine glaciers of the Antarctic Peninsula were retreating, and their retreat was speeding up. Last summer, a British group revisited the Pine Island Glacier finding and found that its rate of retreat had quadrupled between 1995 and 2006.
Role of ice shelf collapse
The retreat of West Antarctica’s glaciers is being accelerated by ice shelf collapse. Ice shelves are the part of a glacier that extends past the grounding line towards the ocean; they are the most vulnerable to warming seas. A longstanding theory in glaciology is that these ice shelves tend to buttress (support the end wall of) glaciers, with their mass slowing the ice movement towards the sea. This was confirmed by the spectacular collapse of the Rhode Island-sized Larsen B shelf along the eastern edge of the Antarctic Peninsula in 2002.
Larsen B ice shelf break-up: Three weeks to crumble a 12,000-year old ice shelf.
The disintegration was dramatic: it took just three weeks to crumble a 12,000-year old ice shelf. Over the next few years, satellite radar data showed that some of the ice streams flowing behind Larsen B had accelerated significantly, while others, still supported by smaller ice shelves, had not. This dynamic process of ice flowing downhill to the sea is what enables Antarctica to continue losing mass even as surface melting declines.
Michael Schodlok, a JPL scientist who models the way ice shelves and the ocean interact, says melting of the underside of the shelf is a pre-requisite to these collapses. Thinning of the ice shelf reduces its buttressing effect on the glacier behind it, allowing glacier flow to speed up. The thinner shelf is also more likely to crack. In the summer, meltwater ponds on the surface can drain into the cracks. Since liquid water is denser than solid ice, enough meltwater on the surface can open the cracks up deeper down into the ice, leading to disintegration of the shelf.
The oceans surrounding Antarctica have been warming, so Schodlok doesn’t doubt that the ice shelves are being undermined by warmer water being brought up from the depths. But he admits that it hasn’t been proven rigorously, because satellites can’t measure underneath the ice.
The globe is getting hotter
Meanwhile, measurements from the Grace satellites confirm that Antarctica is losing mass (Figure 1). Isabella Velicogna of JPL and the University of California, Irvine, uses Grace data to weigh the Antarctic ice sheet from space. Her work shows that the ice sheet is not only losing mass, but it is losing mass at an accelerating rate. “The important message is that it is not a linear trend. A linear trend means you have the same mass loss every year. The fact that it’s above linear, this is the important idea, that ice loss is increasing with time,” she says. And she points out that it isn’t just the Grace data that show accelerating loss; the radar data does, too. “It isn’t just one type of measurement. It’s a series of independent measurements that are giving the same results, which makes it more robust.”
REFERENCES: Based on information at http://climate.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=242&rn=news.xml&rst=2444
Climate change is not something that might happen in the future. It is happening now – since the middle of the 20th century, Australian average temperatures have risen about 1°C. This has been accompanied by an increase in the frequency of heat-waves, a decrease in the numbers of frosts and cold days, and a redistribution of rainfall from eastern Australia and southwest WA to the northwest (www.bom.gov.au/climate/change).
2009 was Australia's second warmest year on record.
Last year (2009) will be remembered for extreme bushfires, dust-storms, lingering rainfall deficiencies, areas of flooding and record-breaking heatwaves (BOM). It was Australia’s second warmest year since high-quality records began in 1910. Last year’s annual mean temperature was almost 1°C above the 1961-90 average, with Victoria, South Australia and NSW all recording their warmest July-December periods on record. The decade just ended (2000-2009) was our warmest on record, continuing a trend where each decade since the 1940s has been warmer than that preceding it (BOM 2010). The likelihood that this warming trend is due to anthropogenic causes is over 90% (IPCC 2007).
Anthropogenic climate change is predicted to have a range of effects on respiratory and allergic diseases over the coming decades, most of them negative.
The possible effects are wide-ranging, and predicted to occur in the following areas:
- Extreme temperature events
- Worsening air pollution
- Altered aeroallergens
- Extreme weather events
Extreme temperature events
The globe is warming and will continue to do so over the coming century. This process will continue, even if rapid and marked reductions in carbon dioxide emissions occur soon, due to the inertia of the global climate system. Mean temperatures will continue to increase, as will climate variability (the range of expected maxima and minima). The effect of this two-fold change will be to significantly increase the number of very hot days for many areas (IPCC 2007).
Each 1°C increase above long-term city averages increases all-cause mortality by up to 3%
The health effects of extreme heat are well-known. The record-breaking 2003 European heat-wave, for example, caused tens-of-thousands of premature deaths across several countries, especially France (McMichael et al 2006). Most affected were the elderly, disadvantaged or chronically ill (especially those with respiratory or cardiovascular disease). There is also evidence from a European study that each 1°C increase above long-term city averages increases all-cause mortality by up to 3% (and respiratory mortality up to 6% – Stafoggia et al 2008).
European temperature anomalies in summer 2003 compared to July 2001 temperatures.
As heat-waves are expected to become more severe, frequent and prolonged as global warming progresses, strategies to reduce the associated morbidity and mortality must become a public health priority (Ayres et al 2009).
A paradoxical effect of increased global temperatures is that winters should become warmer, leading to a modest decrease in cold-related morbidity and mortality .
Worsening air pollution
The relationship between air pollution, climate change and respiratory illness is complex, and more research is needed to allow better predictions to be made. Despite this, enough is known about ground-level ozone, nitrous oxides and particulates to inform future research and mitigation / adaptation strategies.
Ground-level ozone
Ozone is a potent oxidising substance known to have several adverse respiratory effects (Ayres et al 2009):
- Increased new onset asthma
- Decreased lung function
- Exacerbation of COAD
- Allergen sensitisation
- Increased hospital admissions
- Increased all-cause mortality
Ozone (O3) is a component of photochemical smog, produced by the action of sunlight on fossil-fuel combustion products (primarily vehicle exhaust in cities). Its production is increased by warmer temperatures (especially due to the urban heat-island effect), and it is this property that will probably lead to increased ozone formation during the coming century.
Produced by the action of sunlight on exhaust fumes (especially on hot days), high concentrations of ozone found in the Earth's lower atmosphere (troposphere) are hazardous to life.
Although urban areas are most affected, O3 crosses national and even continental boundaries (there is increasing evidence, for example, that Asia is “exporting” its ozone to the USA – Zhang et al 2008). The future effects of this issue are difficult to predict due to warming-induced changes in air circulation and wind patterns.
As hydrocarbon combustion is the main source of ground-level ozone, patterns and levels of future O3 concentrations also become difficult to predict with certainty if carbon-free fuels become dominant.
Other forms of air pollution
Nitrous oxides are produced by high-temperature hydrocarbon combustion (especially in vehicles). They are important, in part, because they produce an enhanced response to inhaled allergens, probably due to bronchial irritation and inflammation (Shea et al 2008).
Small ambient particles are also produced by fossil-fuel combustion. Short-term inhalation of these particles increases cardiopulmonary hospital admissions and mortality, while long-term exposure worsens paediatric asthma and causes higher mortality in adults (Ayres et al 2009). It is difficult to predict future patterns of particle production and exposure, as mitigation strategies (eg electric- or hydrogen-powered vehicles) may significantly reduce their production.
Conversely, expected increases in wildfires, droughts and desertification due to climate change may produce more particles, and they may spread over wider areas (Ayres et al 2009). Wildfires in particular pose many health risks. Apart from the direct threat to life, their smoke may contain plastic and toxic (ie herbicide & pesticide) residues (Shea et al 2008).
Altered aeroallergens
Global warming is already having demonstrable effects on plant behaviour and distribution (IPCC 2007). There has been a general shift polewards and upwards (altitude) of plant habitability zones in many regions, related to warmer conditions. There have also been changes due to altered precipitation patterns and land-use variations.
Flowering times are also changing, with a general trend towards earlier spring flowering (although paradoxically, plants that rely on a longer duration of winter chill to trigger budding are flowering later due to warmer winters).
Research suggests that pollen amount and allergenicity is increasing.
Additionally, pollen appears to be more allergenic, with higher levels of some core proteins (the molecules mainly responsible for triggering allergy – Rom et al 2008). As respiratory allergies may follow dose-response curves, more pollen + more allergenicity = more severe allergies.
Changes in the timing of the pollen season (longer and earlier) may produce worsening allergies if there is overlapping with peak ground-level ozone production in summer.
Other changes due to global-warming include (Reid & Gamble 2009):
Changed wind patterns may disperse pollens in new directions or further than before.
Changed local conditions may alter dust-mite and mould distributions.
Changed agricultural practices may alter the level of pollens related to farming activity (eg rye grass is a component of farm pasture; the mould Alternaria is related to agricultural production).
Changed species makeup of forests and grasslands (whereby one species is replaced by another due to altered microclimate or species invasion) may also change pollen type and load.
All of these phenomena are having the effect of changing pollen distributions. This exposes new populations to novel allergens that will trigger new-onset allergies, as well as worsening existing ones.
Climate change is happening now, and some of the changes described (such as changes in flowering times and geographical range) have already been documented by the IPCC. We know from paleoclimate research that plants react quickly to environmental changes – ice-core and ocean sediment data show that significant vegetation changes (in response to previous climate disruptions) have taken just a decade to occur.
Extreme weather events
Climate change is expected to magnify the hydrological cycle, causing more frequent drought but also more hurricanes, storms and extreme precipitation events (IPCC 2007). It has been known for some time that thunderstorms may cause asthma exacerbations (Ayres 2009). It appears likely that this is due to the disruption of pollen particles, thereby exposing their allergenic cores. Heavier rainfall has the potential to cause flooding and increased mould growth. Both occurred after Hurricane Katrina inundated much of New Orleans. Following such extreme events, it is likely that population displacement, crowding, drinking water contamination and malnutrition will increase respiratory infections, especially pneumonia, and possibly increase TB transmission (Ayres et al 2009).
More frequent flooding, expected as the hydrological cycle intensifies due to global warming, will have adverse health consequences.
Conclusions
The expected impacts on respiratory morbidity and mortality discussed in this article are just a small part of the adverse heath effects predicted to occur over the coming decades due to climate change. The barriers to accepting and acting on anthropogenic global warming are largely psychological rather than scientific, as climate change science is now very robust (IPCC 2007). As health professionals we are well-equipped to deal with risk, uncertainty and levels of evidence, as we do so on a daily basis in clinical practice. We have a unique opportunity to educate and inform our patients, communities, colleagues and politicians about these issues. I believe we have an ethical duty to do so, in order to limit, as far as possible, the expected increased burden of illness that is on the horizon.
Do doctors have an ethical duty to inform society about the health effects of climate change?
References
Ayres JG et al. Climate change and respiratory disease: European Respiratory Society position statement. Eur Resp J 2009; 34: 295-302.
BOM. http://www.bom.gov.au/announcements/media_releases/climate/change/20100105.shtml. Accessed 17.01.2010.
IPCC 2007. Summary for policy-makers (WGI). In Climate Change 2007: The Physical Science Basis. Cambridge University Press NY. 2007.
McMichael AJ et al. Climate change and human health: Present and future risks. Lancet 2006; 367: 859-869.
Reid CE and Gamble JL. Aeroallergens, allergic disease, and climate change: Impacts and adaptation. Ecohealth 2009; published online 12 Nov 2009; accessed 10.01.2010: http://www.springerlink.com/content/mqu4540p63284360
Rom WN et al. Global warming: A challenge to all American Thoracic Society Members (editorial). Am J Respir Crit Care Med 2008; 177: 1053-1057.
Shea KM et al. Climate change and allergic disease. J Allergy Clin Immunol 2008; 122: 443-453.
Stafoggia M et al. Factors affecting in-hospital heat-related mortality: a multi-city case-crossover analysis. J Epidemiol Community Health 2008; 62: 209-215.
Zhang L et al. Transpacific transport of ozone pollution and the effect of recent Asian emission increases on air quality in North America: an integrated analysis using satellite, aircraft, ozonesonde, and surface observations. Atmos Chem Phys 2008; 8: 6117-6136.
A version of this article appeared on the Medical Observer blog on 18.01.2010.
Posted in Respiratory Diseases | Tags: allergy, asthma, health effects of climate change | 1 Comment »
I’ve just finished a major report on ocean acidification. I have published the executive summary below. You can click here to download the ocean acidification report as a pdf (approx 3.8Mb).
Executive Summary
Ocean acidification has been called “the other CO2 problem” and even “global warming’s evil twin”. It occurs when carbon dioxide dissolves in seawater, producing carbonic acid (H2CO3).
Carbonic acid rapidly dissociates to produce hydrogen (H+) and bicarbonate ions (HCO3-). The hydrogen ions so produced combine with carbonate ions(CO3), sourced from calcium carbonate (CaCO3) to form more bicarbonate. This reduces the amount of available calcium carbonate.
Ocean acidification must be recognized for what it is – A global challenge of unprecedented scale and importance that requires immediate action to halt the trend of increasing acidification (EPOCA 2009).
Calcium carbonate is used by many marine organisms (including coral, oysters, mussels and many types of plankton) to form shells and skeletons. Less calcium carbonate makes it harder for these organisms to precipitate calcium.
As the oceans have absorbed about one-third of all anthropogenic carbon dioxide, they are now 30% more acidic than in pre-industrial times. This drop in pH is already reducing calcification rates of some marine calcifiers, especially those in colder waters (which can absorb more CO2 than warmer seawater).
Many ocean species rely on calcium to make shells and skeletons.
If CO2 emissions continue on their current trajectory, oceans will be 3x – 5x more acidic than pre-industrial levels by 2100. This will be more acidic than at any time in t he last 300 million years. The effects of this are unprecedented, but likely to be overwhelmingly negative – major impacts that will probably ramify upwards through marine food chains to apex predators, and be accompanied by the widespread extinction of some ocean species (especially benthic plankton).
Ocean acidification could trigger a chain reaction of impacts through the marine food web, beginning with larval fish and shellfish, which are particularly vulnerable (EPOCA 2009)
Coral reefs will be placed under increasing threat as acidification progresses. If present emission rates continue it is thought that they will start to dissolve (ie calcium carbonate will be reabsorbed into solution) by 2050.
Because of major inertia in the system, the acidification process is essentially irreversible over any time frame meaningful to us (ie > 10,000 years). Likewise, even if we were to stop all CO2 emissions tomorrow, ocean pH would continue to drop for some time (at least decades) as it reached a new carbon equilibrium with the atmosphere.
Because acidification is independent of carbon dioxide’s effect as a greenhouse gas, geo-engineering strategies that aim to cool the planet without removing atmospheric CO2 will have no effect on ocean acidification. Approaches to offset acidification (such as the application of crushed limestone to the oceans) would need to be at such massive scales that they would be prohibitively expensive (both economically and environmentally).
The only real way to fix this problem is to stop emitting carbon dioxide.
Acidification will have impacts on key Australian marine ecosystems such as those of the Southern Ocean, marine protected areas on the southern margins of the Australian continent (the Great Australian Bight and Tasmanian seamounts) and, eventually the Great Barrier Reef (ACE-CRC 2008)
Now take action.
- We don’t have long to change things around.
- Ocean acidification is already making the calcified parts of some sea creatures thinner and lighter. It is happening right now, independent of global warming.
- Coral reefs are going to start disappearing by 2050 at the latest.
- Acidification has the same solution as global warming – rapid emissions reduction.
- Due to the long lag-times in the system, the quicker we reduce carbon dioxide emissions, the more effect it will have in the future.
Here’s what you can do – Tell someone about this problem. Do something today!!!Visit my ocean acidification resources page for videos and links to major learned reports on this topic. Watch this video:
